With the development of optical fiber communication technology, in the field of optical fiber communication, it is required to load low-frequency signal on the original high-speed service channel. For example, the International Organization for Standardization, FSAN, proposed to add an Auxiliary Management and Control Channel (AMCC) to a point-to-point dense wavelength division multiplexing passive optical network. The transmission rate of AMCC is generally below 100 Kbit/s, i.e., belonging to low-frequency signal. Therefore, PTP WDM PON network is required to bear both the original high-speed service signal and low-frequency signal such as AMCC.
In the PTP WDM PON network, the optical signal is received and transmitted by an optical module. However, in the prior art, the optical module can only receive and transmit the high-frequency digital service signal, but cannot receive or transmit the low-frequency signal.
Therefore, the optical module in the prior art cannot meet the requirement of bearing both the high-frequency signal and the low-frequency signal simultaneously.